RFC: Add Arch Linux support and a bunch of  minor fixes

I spent some time working on these manifests to make them work for my particular platform and buildroot. Let me begin by saying that I'm sorry that the commit is a bit of a mess which touches everything - I sort of just made the changes as errors popped up or when I noticed something off around the are where I was already editing. 

The primary aim of the changes was to add Arch Linux support. I also changed the way /var was handled (replaced it with a new parameter) and added a "creates" statement to the supervisord to avoid having puppet spawning multiple instances. Not too happy about that last one, since it depends on having the correct socket location in the buildroot, and I don't know plone or buildouts well enough to say what the common idiom is.
Please consider this merge request a RFC and feel free to nag about the patch.

On an unrelated note - is there any plans to add the module to the puppet forge?